Scared

Ana
I don't know what's going on, my period was supposed to come around the 27 or 28 of last month ( February) and it didn't, obviously I started to freak out and think about being pregnant and did many tests but they all came out negative. The same thing happened to me last month ( January) my period came after almost 50 days from
Last day to the first of the new period. I had never been that way
I'm scared it could be something worst and more serious
I've having cramps for many days now and very sore breasts 
Please help